Structural and electronic changes in Ga-In and Ga-Sn alloys on melting

The melting behaviour of surface slabs of Ga-In and Ga-Sn is studied using periodic density functional theory and ab initio molecular dynamics. Analysis of the structure and electronics of the solid and liquid phases gives insight into the properties of these alloys, and why they may act as promising CO2 reduction catalysts. We report melting points for slabs of hexa-layer Ga-In (386 K) and Ga-Sn (349 K) that are substantially lower than the pure hexa-layer Ga system (433 K), and attribute the difference to the degree to which the dopant (In or Sn) disrupts the layered Ga network. In molecular dynamics trajectories of the liquid structures, we find that dopant tends to migrate from the centre of the slab towards the surface and accumulate there. Bader charge calculations reveal that the surface dopant atoms have increased positive charge, and density of states analyses suggest the liquid alloys maintain metallic electronic behaviour. Thus, surface In and Sn may provide good binding sites for intermediates in CO2 reduction. This work contributes to our understanding of the properties of liquid metal systems, and provides a foundation for modelling catalysis on these materials.

Automated summary

The melting behavior of Ga-In and Ga-Sn surface slabs was studied using periodic density functional theory and ab initio molecular dynamics. The analysis of structure and electronics revealed insights into the properties of these alloys and their potential as CO2 reduction catalysts. The research showed that the melting points of hexa-layer Ga-In and Ga-Sn were lower than pure hexa-layer Ga, attributed to the disruptive effect of the dopants on the Ga network. Molecular dynamics simulations showed that dopants migrated to and accumulated on the surface of the slabs. The positive charge on the surface dopant atoms and the metallic electronic behavior of the liquid alloys suggested good binding sites for CO2 reduction intermediates.